Derivatives of tylosin and its related macrolides have been shown to be effective against infections in poultry, cattle and pigs caused by certain gram-positive and gram-negative bacteria: Kirst et al., U.S. Pat. No. 4,920,103; Tao et al., U.S. Pat. No. 4,921,947; Kirst et al., U.K. Patent Application GB 2135670A.